The present invention relates to a daisy wheel type printing device.
A daisy printing wheel is employed, for example, in the printing device associated with an electronic typewriter. The daisy printing wheel used in the printing device of this type is usually formed of a plurality of rectangular supporting plates arranged to extend radially from the center thereof. This printing wheel is arranged in a position facing a platen and driven by a stepping motor. When a character is to be printed, the printing wheel is rotatably driven by the stepping motor, the type of the character to be printed is set in the printing position facing the paper on the platen, and the type is then struck by a printing hammer driven by a solenoid coil, thereby printing the desired character on the paper through an ink ribbon.
Assuming that an angle formed between the adjacent two supporting plates of the daisy printing wheel is one pitch, one revolution of a printing wheel formed, for example, of 100 supporting plates corresponds to 100 pitches. It is, therefore, sometimes necessary to rotatably move the printing wheel from zero pitch (0.degree.) to 50 pitches (180.degree.) when a desired character is to be printed. In this case, in order to rotate the printing wheel to a position designated by the desired character to be printed as soon as possible, the printing wheel is rotated by a rotary speed pattern determined in advance in accordance with the rotation distance (or the the number of moving pitches) of the printing wheel. When this printing wheel has been completely driven to the designated position, a hunting type of vibration occurs at the supporting plates and type. Therefore, a quiescent time which is slightly longer than the longest time required for attenuating the vibration to a sufficiently small value is set. The printing wheel is driven after this quiescent time has elapsed after the printing wheel has arrived at the designated position. However, the vibration generated at the supporting plates and type of the printing wheel might be attenuated to a sufficiently small value within a time that is much shorter than the preset quiescent time when the printing wheel is driven to a designated position in accordance with a predetermined speed pattern. Even in this case, the printing hammer is not driven until the quiescent time has elapsed, and the average printing speed is accordingly lowered.